GREEN BAY, Wis. 
Mitt Romney is looking for a sweep in Tuesday's three Republican primaries, expecting to tighten his grasp on the party's nomination.

Regardless of the outcome in Wisconsin, Maryland and Washington, D.C., the GOP front-runner is rapidly shifting toward the general election - and the challenges of President Barack Obama's better-financed and better-organized opposition.

These days, Romney is ignoring his Republican rivals and taking it to the Democratic president, whom he accused Monday of "crushing dreams" with a "government-centered society."

"He takes his political inspiration from the capitals of Europe," Romney told supporters in Green Bay, Wis., one day before the latest primaries in the GOP fight. "His version of a perfect world is a big-spending big government."

Romney's rhetoric aside, the grinding Republican primary, already 3 months old, has complicated his ability to re-focus his broader organization toward Obama. Aides concede that staff building and fundraising for the fall match-up are lagging.

Romney's recent string of high-dollar California fundraisers was limited to raising money only for the Republican primary contests. Aides are only beginning to take steps to raise cash to use against Obama, who has been aggressively fundraising and distributed staff on the ground in almost every state in the nation.

The delay has given Obama a massive head start. The disparity is staggering.

At the end of February, Obama reported $84.7 million in his campaign account compared to Romney's $7.3 million. Obama has more than 530 paid staff compared to roughly 100 for Romney.

A fading Rick Santorum, also campaigning in Wisconsin on Monday, said that Romney has essentially bought his success by outspending the competition.

Romney and his allies have spent a combined $53 million on television advertising so far this election cycle compared to just $27 million from his three Republican competitors combined, according to data compiled by the media tracking firm SMG Delta.

Santorum's team, having narrowly lost a string of high-profile contests, spent just $9 million.

"With almost unlimited resources, Gov. Romney has not proven to be very effective," Santorum said Monday as he predicted a possible upset in Wisconsin. "The only way he's been successful in winning the primaries is by just bludgeoning his opponents by an overwhelming money advantage - something he's not going to have in the general election."

In the primary race, Romney has a huge advantage in delegates. On Monday, The Associated Press count had Romney with exactly half the delegates needed to win the nomination, 572, and twice as many delegates as Santorum.

For the fall campaign, Romney's presidential hopes may rest, at least in part, upon the ability of the Republican National Committee to give him a running start. The RNC, beset by problems of its own in recent years, says it's ready to meet the challenge. Yet party officials acknowledge limitations. General election fundraising in particular has suffered without a nominee.

The RNC last week announced it had filled a "presidential trust" with $21 million to spend in coordination with the nominee. But there is no limit on what the committee can raise and spend on its own to support the party's presidential contender.

"There are donors that are sitting on the sidelines right now," said RNC political director Rick Wiley.

Romney's campaign has also been anxious to be able to raise money for the party itself when it holds finance events - donors can cut checks of up to $30,800 to the party committee. But without the nomination, they haven't been able to ask for that money yet.

The complications extend beyond fundraising.

Wiley said the committee's nationwide network of "victory centers" might not be fully operational until August unless a nominee secures the nomination soon.

"I think you will see as soon as you get a nominee, an accelerated ramp-up of staff," Wiley said. "Right now everyone's out the door by August, but I can see a scenario where everyone was out the door by June or July if we had a nominee in the next 30 days or so."

Late last month, the RNC opened general election offices in North Carolina and Virginia and in Florida, a critical swing state where the committee now has 10 offices, according to Wiley. And this week offices are set to open in Nevada, Colorado, New Mexico and Michigan.

Romney's campaign, which would assume control of the offices should he claim the nomination, has been slow to implement a plan to reach Hispanic voters, outside of a handful of states, such as Florida. The RNC separately is instituting Hispanic state directors this week in Florida, North Carolina, Virginia, Colorado, New Mexico and Nevada.

While the RNC cannot pick sides before a nominee emerges, Romney's campaign has benefited from a network of informal alliances. Many members of Romney's senior staff have either worked for, or closely with, the RNC for years.

Wiley, for example, worked under Romney's political director, Rich Beeson, for more than a decade. Beeson was the RNC's political director four years ago.

Beeson said that even without the RNC's help, the Romney campaign has built a network of donors, prominent supporters and voter files that will translate to the general election.

"You don't go into Florida and bank as many early absentee votes and do what we did statewide without leaving behind a pretty good organization that's still in place and will be there in a general election," Beeson said. "Same with Ohio, same with Michigan, same with Colorado, with Nevada - just sort of go down the list. There is an infrastructure in place in every one of those states."

In some cases, however, the campaign is not as prepared as Beeson would like.

Romney's campaign often moved staff from state to state as the primary progressed. Much of Romney's Florida senior team, for example, left the state for Ohio as soon as voting finished - and then moved on yet again from Ohio to Illinois and then to Wisconsin.

They are eager to expand, however. The campaign has a list of Republican operatives ready to hire as soon as Romney has general election money to pay them. The campaign's Boston office occupies two floors but is preparing to fill a third.

In Chicago, Obama's team has 300 paid staffers already at work inside the president's re-election headquarters. They're anticipating a general election against Romney.

"We are building the largest grassroots campaign in history on the ground," Obama campaign spokesman Ben LaBolt said. "Ultimately, our supporters talking to their networks about the two candidates, their records and their visions for the country will be much more persuasive than any television spot."